Process and apparatus for carbonizing powdered coal



Dec. 5, 1933. A. H. DAYIS, JR 75 PROCESS AND APPARATU FOR CARBONIEZING POWDERED COAL Filed Aug; 15, 1928 v Patented n... 5, 1933 PATENT. OFFICE PROCESS AND APPARATUS FOR CARBONIZ- ING POWDERED COAL Archibald B. Davis, In, Buffalo, N.Y., asslgnorto National Aniline & Chemical Company Inc.,

New York, N. 1., a corporation of New York Application August 15, 1928. Serial No. 299,100 1': Claims. (011202-13) This invention relates the carbonizationof coal in powdered form and the production of byproducts therefrom, and to a coke which is suitable for use as a powdered fuel without grinding;

.5 The invention further contemplates the process and apparatus for the carbonization of powdered coal in an electrostatic field to produce a powdered coke and by-products.

The production of powdered coke has heretofore been accompanied by serious diiilculties which have greatly restricted its use as a fuel. In the heretofore known processes of carbonizing coal, the coal is heated in retorts to drive off the volatile matter, leaving a residue of coke. The coke thus obtained is rather hard, very gritty and exceedingly abrasive, and consequently it is neither practical nor economical to subject it to a grinding or pulverizing operation. On the other hand, coal is fairly easily pulverized and attempts have been made to produce a powdered coke in a carbonizing process using powdered coal as the starting material. These attempts have not been successful due to the fact that the particles of powdered coal will agglomerate and coalesce together under the influence of the high temperature of carbonization and yield a coke which is still so coarse that it must be pulverized before use as a powdered fuel.

Further, a difiiculty encountered in the burning of coke, when used as a fuel, arises in the fact that ordinarily powdered coke cannot be burned in the same apparatus as is used for burning powdered coal.

It is also known that coal may be carbonized at low temperatures to yield products such as benzol, tar-acid oils and ammonia, a coke which is not so dense as that produced in the carbonization of coal at higher temperatures, and a considerable amount of fuel gas. The products, i.e., benzol, tar-acids, ammonia, etc., which are more valuable as articles of commerce than as a fuel are consumed as fuel and lost when coal is burned in either lump or powdered form. It is therefore highly desirable to carry out the burning-of coal in such a manner that these valuable products can be saved and a coke be produced which will not require pulverization to adapt it for use as a powdered fuel.

One object of the present invention therefore contemplates the carbonization of coal under such conditions that the coke produced is in a finely divided state and requires no grinding or further treatment to adapt it for use as a powdered fuel. Another object contemplates the use of coal in powdered form as a fuel under such conditions that the volatile by-products, or a part of them, will not be consumed but can be saved. Another object-contemplates the low temperature carbonization of coal in powdered form with the production of coke in a finely divided state which will require no grinding or further treatment to adapt it for use asa powdered fuel.

Another object contemplates the cyclic utilization of the heat carried by the hot furnace gases to produce coke and by-products from powdered coal, and the burning of the coke in powdered form without undue loss of heat, Another object contemplates the burning of the powdered coke in admixture with a fuel gas to help maintain the coke at ignition temperature.

Another object of my invention contemplates a continuous processand-an apparatus for carbonizing coal wherein the coal and coke are handled substantially entirely in suspension during carbonization. Another object involves the carbonization of particles of coal under the influence of an electrostatic field whereby agglomeration and coalescing together of the particles is substantially prevented, or practically so, and includes the apparatus for carrying out the carbonization. Another object contemplates the application of the principle underlying electrical precipitation to the carbonization, particularly at low temperatures, of coal in powdered form to maintain the particles as such in suspension or dispersion during the carbonizing process and to separate the coke dust from the volatile products after carbonization is completed but prior to condensation of the liquefiable constituents.

Other objects of my invention include -the flash carbonization of powdered coal whereby a coke is produced which is more free from volatile substituents than that produced by other, particularly low temperature, carbonization processes; the use of live hot furnace gases as the principal source of heat to effect the carbonization of coal; and the partial combustion of coal to assist in maintaining the proper carbonization temperature. .These and other objects will be readily apparent from a consideration of the following specification taken in connection with the drawing which shows in elevation a general arrange- 'ment of the apparatus used in carrying out the invention, parts being shown in section.

Referring to the drawing, the numeral 1 repreother suitable manner.

coal is delivered through the pipe line 3 and through a mixing nozzle 4 of any suitable construction into thecarbonizing chamber 5. Hot live furnace gas is drawn from the furnace 6 through pipe 7 by fan 8 and enters the mixing nozzle 4 where the hot furnace gases and powdered coal are mixed and the mixture is then introduced into the carbonizing chamber 5.

The quantity of the furnace gases entering chamber 5 must be regulated to produce the proper carbonizing temperature in the chamber, which temperature is in the vicinity of 500-700 F. in low temperature carbonizations and about 18002000 F. in high temperature carboniza tions. If it is found to be diflicult to introduce sumcient heat into the chamber to carbonize the coal at the required temperature by means of the furnace gases, sufficient oxygen or air, which may be preheated, may be introduced into the carbonizing chamber by means of the pipe 9 to effeet a combustion of a part of the pulverized coal, or of the gases, or both, in the chamber and complete the carbonization by the aid of the heat thus produced. The rate of flow of the pulverized coal, furnace gases and air into chamber 5 the required temperature while it is passing therethrough in admixture with the furnace gas. In

the drawing, this chamber is shown as being in the horizontal position but it may be inclined or vertical. The volatile gases and hydrocarbons produced as by-products in the carbonization pass out through the conduit 10 and through the condenser 11 where the liquefiable constituents are condensed and collected in the collector 12. The uncondensed gases are drawn through the duct 13 by the pump 14 and from there are blown to the burner 15 and into the furnace 6 where they are burned to give up their heat of combustion. The furnace 6 may be used in connection with a boiler to produce steam or the heat of combustion of the gases may be utilized in any A portion of the hot furnace gases are by-passed through '7 back into the chamber 5 where their heat content is utilized, the remainder of the gases being burned in the furnace and pass out through the flue 16.

The coke produced in the carbonization chamher is deposited on the conveyor 17 in powdered form by means presently to be described, and is preferably directed into the bin 18 and thence through the passage 18" by means of the screw conveyor 18', or other suitable means, to the burner 15 where it is mixed with the uncondensed gases from the carbonizer, and with oxygen or air supplied by the pump 19, and burned in the furnace 6. The operation of the pumps 8, 14 and 19 are so regulated that the volatile gases and hydrocarbons will not escape through passage 18" but will substantially all pass out through conduit 10. By mixing the powdered coke with the fuel gas and igniting the mixture, the coke is kept constantly at an ignition temperature and can be completely burned. It is to be understood, however, that where it is desired to produce coke for future use, the coke may be stored, in which case, however, heat for carbonization may be supplied by the burning of the fuel gas produced or by any other suitable means. I

It is highly desirable to secure the dered form so-that no further grinding will be necessary, to permit the use of the coke as a powdered fuel. In order to prevent the coalescence of the particles of coke and coal in the carbonizer, the following construction is provided. A strong electrostatic field is induced in the chamber 5 by means of the electrically charged plates 20 forming one electrode of an electrical precipitation apparatus. The conveyor 1'1 forms the other electrode. As is well known, an electrical precipitator may be used to produce a dispersion or suspension of particles as well as a precipitatiomand its use. in this connection is contemplated. The highly charged plates 20 induce by contact therewith and with the ionized particles within the electrostatic field a like electrostatic charge on all of the coal particles in the chamber and thereby cause a mutual repulsion. between the particles which prevents them from agglomerating together during carbonization. During carbonization, the particles of coal give up .their volatile constituents and are converted into coke without losing their electrostatic charges. After carbonization, the charged particles of coke are carried along through the chamber and are attracted by the collector or conveyor 17 carrying an unlike electrical charge, where their charges are neutralized and the particles are deposited as a powder and carried out of the chamber into the bin 18, to be burned or disposed of in any suitable manner.

coke in pow- I have not described my invention in connecnot wish to be limited to any particular type and their construction and operation are known to those skilled in the art. It will also be understood that the invention includes the production of coke and fuel gas which may be separately collected and stored by any suitable modification of the apparatus. sary for carbonization will be secured from a different source. It will be further understood that there may be a series of carbonizers operated, and that the electical disperser may consist of a series of plates instead of only two as shown. The invention may be applied either to the high or low temperature carbonization of coal, and is not to be limited except as defined in the following claims. v r

I claim:

1. In the carbonization of pulverized coal, the process which comprises keeping the particles of pulverized coal from bodily contact with each other by inducing a like electrostatic charge upon each particle and subjecting said particles while thus separated to acarbonizing temperature.

2. In the carbonization of pulverized coal, the process which comprises separating particles of the pulverized coal from bodily contact with each other by inducing a like electrostatic'charge upon said particles, subjecting the electrified particles to a carbonizing temperature, and subsequently neutralizing the electrical charges on. said electrified particles.

3. In the carbonization of pulverized coal, the process which comprises separating particles of the pulverized coal from bodily contact with each other by inducing a like electrostatic charge upon said particles, heating the electrified particles to carbonizing temperature by a heated gas, and

process which comprises pulverizing coal, separating particles of the pulverized coal from bodily contact with each other by inducing like electrostatic charges upon said particles, subjecting the particles to a carbonizing temperature by means of a hot gas, separating the particles of coke produced from the volatile by-products, condensing out liquefiable constituents from the volatile products, mixing the uncondensed gases with the coke produced, and burning the mixture and utilizing a portion of the resulting hot combustion gases to carbonize other portions of pulverized coal.

6. In the carbonization of powdered coal, the process which comprises pulverizing coal, separating particles of the pulverized coal from bodily contact with each other by inducinglike electrostatic charges upon said particles, subjecting said charged particles to a carbonizing temperature by means of a hot gas, neutralizing the electrical charges upon said particles to separate the par ticles of coke produced from the, volatile byproducts, condensing out liquefiable constituents from the volatile products, mixing the uncondensed gases with the coke produced and burning the mixture, and utilizing a portion of the result-' ing hot combustion gases to carbonize other portions of pulverized coal.

7. An apparatus for carbonizing coal comprising means for pulverizing coal, means for suspending the pulverized coal in a gaseous medium, means for subjecting the pulverized coal while in suspension to the heating action of a hot gas for carbonizing the same, means for separating the particles of coke produced from the volatile by-products, means for condensing out liquefiable constituents from the volatile products,

means for mixing the uncondensed gases with the coke produced, means for burning the mixture, and means for directing a part of the hot gases produced in the burning mixture into the carbonizing means.

8. In the carbonization of pulverized coal, the process which comprises inducing an electrostatic field, introducing particles of coal into said field, whereby like electrical charges are induced upon the particles to maintain said particles bodily separated from each other, and subjecting said particles while in said electrostatic field to a carbonizing temperature.

9. In the carbonization of pulverized coal, the process which comprises inducing an electrostatic field, introducing particles of coal into said field, whereby like'electrical charges are induced upon the particles to maintain the particles bodily separated from each other, subjecting said particles while in said electrostatic field to a carbonizing temperature, removing the carbonized particles from the carbonizing sphere, and neutralizing the electrical charges on the carbonized particles.

10. In the carbonization of pulverized coal, the

process which comprises inducing an electrostatic field, introducing particles of coal into said field, whereby like electrical charges are induced upon the particles to maintain the particles bodily separated from each other, heating the electrified particles to carbonizing temperature by means of a heated gas, and neutralizing the electrical charges on the carbonized particles.

11. In the carbonization of pulverized coal, the process which comprises inducing an electrostatic field between two separated electrodes, introducing particles of coal into said field whereby the particles are kept bodily separated by the electrical charges induced thereon, heating said electrified particles to carbonizing temperature by a heated gas," oxidizing a portion of said particles to assist in maintaining the carbonizing \temperature, and neutralizing the electrical charges on the carbonized particles.

12. In the carbonization of powdered coal, the process which comprises pulverizing coal, separating particles of the pulverized coal from bodily contact with each other by inducing like electrostatic charges upon said particles, subjecting said chargedparticles to a carbonizing temperature by means of a hot gas, neutralizing the electrical charges upon said particles to separate the resulting particles of coke from the volatile byproducts, and condensing out liquefiable constituents from the volatile by-products.

13. In the carbonization of powdered coal, the

process which comprises pulverizing coal, separating particles of the pulverized coal from bodily contact with each other by inducing like electrostatic charges upon said particles, subjecting said charged particles to a carbonizing temperature by means of a hot gas, neutralizing the,

electrical charges upon said particles to separate the resulting particles of coke from the volatile by-products, condensing out liquefiable constituents from the volatile by-products, mixing the uncondensed gases with the coke produced, and burning the mixture. 14. Apparatus for carbonizing coal comprising a carbonization chamber, means for introducing pulverized coal into said chamber, means for introducing a .hot gas into said chamber to effect carbonization of the pulverized coal, means for inducing an electrical charge upon the particles of coal to keep them separate from each other 'during carbonization, means to neutralize the electrical charge carried by the particles of coke produced, and means for withdrawing the coke from the carbonization chamber.

15. Apparatus for the carbonization of coal,

comprising a carbonizing chamber, means for introducing coal into said chamber, means for particles of coke produced to separate them from the volatile by-products.

16. An apparatus for the carbonization of coal comprising a carbonization chamber, means for introducing pulverized coal into said chamber, a

plate forming one electrode of an electrical precipitator positioned to induce like electrical -charges upon particles of coal introduced into said chamber, a conveyer spaced from said plates forming the other electrode of said electrical precipitator positioned to attract and collect the charged particles of coke produced by the carbonization of the pulverized coal, and means for electrically charging said electrodes.

17. In an apparatus for carbonizing coal, the each other. during carbonization, and means in combination which comprises a carbonization the path of movement of coke produced by carchamber, means for introducing pulverized coal bonization oi! coal in said chamber to neutralize into said chamber, means Iorinducing an electhe electrical charge carried by the particles of 5 trical char ze upon particles of coal introduced coke. 80

into said hamber to keep them separate from ARCHIBALD H.- DAVIS, JRt 

